Page 209 - Like me, or else... - Michelle Achterberg

MRI scan quantity and quality in childhood
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after the MRI scan (M= 2.62, SD= 1.49), compared to before the MRI simulation (M= 3.84, SD= 1.28; F (491) =124.65, p<.001, all Bonferroni corrected pair-wise comparisons p<.05). Ratings of tension by the researchers and parents showed a similar pattern (Figure 1b) and were significantly correlated with ratings of children (r-range= .23-.80, see Table S1). Scanner related distress (before simulation and before the MRI scan, for excitement and tension) was more strongly correlated between children and researchers (r-range: .70-.80, Table S1), than between children and parents (r-range .23-.42, Table S1), but it should be noted that the child and researcher filled in the rating at the same form and therefore were not independent. The multi-informant scores (estimated emotional state averaged across child and parent) of tension and excitement were significantly negatively correlated: r=-.33, p<.001 before MRI simulation, and r=- .35, p<.001 before the MRI scan.
Genetic influences on scanner related distress
To investigate genetic and environmental influences on scanner related distress, we calculated Pearson’s within-twin correlations for MZ and DZ twins and performed behavioral genetic analyses. Within-twin correlations for the multi- informant ratings of scanner related distress (tension and excitement; before MRI simulation and before MRI scan) were similar for MZ and DZ twins (rmz range=.24- .58; rdz range=.22-.48; all p’s<.05, see Table 2). Behavioral genetic analyses revealed that scanner related distress was mostly explained by environmental factors, both the shared environment (C-range=23-47%) as well as the unique environment/measurement error (E-range=45-77%), with little to no influence of genetics (A-range= 2-27%) (Table 2).
MRI Quantity
Scan quantity
Of the 512 included participants, 24 children (4.7%) never started with the MRI scan due to MRI contra indications (n=6); lack of parental consent (n=4); technical error (n=1), or substantial anxiety (n=13), see Table S2. As can be seen in Table S2 and Figure 3a, there was a drop in scan quantity (i.e. the number of scans completed) after the structural anatomy scan (from 94% to 88%). Scan quantity decreased because some children reported tiredness (n=18) or due to time constraints (i.e. the reserved time was over; n=12). For some children the DTI scans were skipped and only the RS-fMRI scan was acquired (n=12), as the RS- fMRI run was shorter in duration (5 minutes compared to 2*5 minutes DTI). To investigate age and gender effects on scan quantity we compared participants who completed all scans (age M=7.96, SD=0.67; 48% boys; n=433), and participants who missed one or more scans (excluding participants who missed scans due to time constraints; age M=7.84, SD=0.66; 59% boys, n=39). However, we found no effects of age (t(470)=-1.08, p=.28) or gender (χ(1, N=472)=1.86,
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